Between-population variation in haemocyanin subunit composition of the beachflea Orchestia gammarellus (Crustacea: Amphipoda)

The subunit composition of haemocyanin (Hc) from the semiterrestrial beachflea Orchestia gammarellus exhibited less heterogeneity and less (qualitative) between-individual variation than most decapod Hcs. While between-population variation was detected, no clear trends in He subunit composition from four populations along a salinity gradient were observed. Salinity had no detectable effect on He subunit composition or HcO 2 binding in the laboratory. The degree of phenotypic variation in laboratory-held beachfleas was less than that displayed by any of the natural populations examined. Furthermore, examination of the O 2 binding characteristics of five of the most common He phenotypes showed that each phenotype had the same O 2 binding properties. Differences in He subunit composition between individuals and between populations may exist, but it should not be automatically assumed that such variation will have consequences for intrinsic He O 2 binding properties.